Protractor polygon



`J. DUGAN PRQTRAGTOR PoLYGoN J DUGAN PROTRACTOR POLYGON sept. 21, 1926.1,600,666

Filed oct. 2o.. 1925 2 snms-sheew4 INVENToR f Patented Sept. 21, 1926.vi

UNITED Strass FCf-p 1 JOSEPH DUGAN, or Los ANGELES, oAmFoiaNImAssreNoR'ro LoUIsAijUGAN, oF v Los ANGELES, CALIFORNIA.

'PRoTRAo'roRVPoLYGoN v Appnoation filed october 2o, 1925.Y serial No,eases,

y f The invention'forming thesubject ymatter lying in the edges ofKV thesides OQ, and vvNL,

-of'this applicationr is designed to replace respectively,,ofthe` rulemember 6i. Each 50 ordinary vdrafting triangles in common use; Scale isincluded in a quadrant oiikafcircle; 'i

and tofcombine in a single instrument eX- the scale 7 beginning at thepoint T in aline- I tremely simple .and eticient means or'setment Withthe line OQ andfending" at the.

ting Ioil' angles of any `desired degree, bisectvPOH R, spaced slightlyaway flQHl. m192111-v ing and doubling angles, finding centers of gle B;and the scale8 beginningl at the point 55 arcs, and for drawing circles.-U in alinement With line LNand endingat In the drawing v the point S,spaced awayl from theangleD.i.: Figure lis" an Velevation of one face'of The two arcs'have the same-length radius the protractor-polygon; andi i and are symmetrically placed relative tothe Figure 2 is an elevationof a modification center line AB. f f i i thereof. y Y j Slots 11 are-cut in the member 6 andfhave Y 'As shown inrFig. l, the instrumentcom-y their edges 12 in alinemen-t With the lineAC,

.15 'Prises VaV Plate 1 of anyl kdesired material, Yand $021195 9 and10( a'ellovded OHP' preferably transparent; This plate 1 is cutI positesides of the member-6. A seriesof to forni a, quadrilateral ABCD .havingthe p apertures 13are formed on the line yAC be- 65 sides AB and ADequal to'. each other and tween the point A and the starting line 13 atright angles to each other, and having the of the scales. As shown inFig. 1, the slots 20 sides BG and CD equal to eachother and at 11 areeach one inch in-length and are aran angle of ksixty'degreesto eachother. ranged between alternate inch graduations. This arrangment of'ysides obviouslyv makes TheV center .of the apertureof theV serie`s13 70the remaining angles ofthe quadrilateral nearest the line 13isspacedone-eighth ont' y equalto each other and equal to one hunan inchtherefrom and theycenterf'ofeach- .A dred and tive degrees. i apertureis similarly spaced from the ,ceni Triangular'portions 2, 3, 4, and 5are cut ters of the adjacent apertures. Y i' n 'l out of the plate 1symmetrically on opposite Particular attention'is directed to the fact75 "sides of a line joining the angles and C. that all the elements ofthis protractor-polyfy The triangles 2 and 3 have their sides GQ gon,With the ysingle exception oiitheslots.;` 30 and NL parallel to theyline 12 bisecting the 11, are symmetricallygarranged onl I`oppositeangles A and C, their sides QP and LM'insides ofthe line AG and areidentical inevj clined at an angle of fifteen degreesV to line eryrespect. This symmetry of partsfobvil80 12, and their sides PO and MNparallel to ates allnecessity for floppingthe polygon the quadrilateralsides BA and DA, respecfrom one face to another in setting ol"lines.135, tively. l y inclined in `opposite,directions,to ai. common l Thetriangular portions 1 and 5 are'also reference line.'4 Y' I cut out-ofthe plate 1 symmetrically of the Assuming the'V side positioned 85 f lcenter line AC, and have the sides EF and against the edge of a T-squarebladeit Will y JH inclined at an Vangle of ive degrees to be obviousifromthe geometry ofthet figure? thesides CDl and CB respectively. ofthe that lines EF, EG, LM, .LN` or Q0, QP, v. A. quadrilateral; withthesides HK and EG HK, HJ, and CB are inclined,y respectively,

i inclined at an'angle of live degrees to the at angles of iive,ten,fifteen, thirty, orty- 90 l Asides JH and EF, respectively, the sides KJfive, titty, titty-tive, and sixty degrees to side y and GF beingparallel to sides AB and AD, CD lorthe edge of the T-square blade, and`.A respectively. thatjthe edge AD is inclined at anangle of i Thequa-'drilateral sides AB and AD are seventy-tive degrees to said blade.With each provided With protractor scales 7 and the side AD against theTfsquare blade, the `95 having their respective centers 9 and 10 linesAB, BG,JH, KH,PQ,OQ or NIMH f' ML, GE, FE, and DC will be inclined, re-

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limited in any Way to any specific numberA ofk Wh-ich a .line is toangle, rthen swing :the polygon around this spectively, at angles ofninety, fifteen, twenty, twenty-five, thirty, forty-five, sixty,sixiive, seventy, and seventy-five degrees to the edge of the T-squareblade. This means that fourteen angles between Zero and ninetydegreescan be set olf directly in eitherv Vforty-five-ninety andthirty-sixty-ninety .de-

gree-triangles. n

'The symmetrical arrangement the protractor'- scales relative to theline AB ada-pts the Yinstrument for bisecting lines, for bisecting anddoubling angles, and-for drawing the diameters of .circles .and arcs`and lind- 1ngthe` centers thereof. The 'protractor scales be used inthe ordinary yWay by pricling ojpoints. Itis preferable to nse 4 them bypositioning one of the center points 9 or l0 at the point in a givenline ythrough be drawn at any desired point until the desired,graduation mark on .the scale f7 orScoincides with the `given line, inwhich :position a line may be drawn along the edge olf the member 6through the point and at the-desired angle indicated by the graduationon the protractor scale.

The invention is not to be conside-red Aas tri-angular cut-outs intheplate 1, as the arrangement shown inthe drawing was selected mainlyto keep the'instrument Within reasonable bounds of simplicity, Vand togive the g maximum Working lengths of ruling edges ,consistent With thesize of the instrument.

'Y The bigj inventive: idea lies in .the symmetry ofthe 4parts relativev to the-center line of I Vquadr'ilateral, and it is this symmetry thatgives the extremely simple instrument so `many uses.`

The peculiar arrangement of the ruling member 6 with vrespectto theprotractor scales makes it the equivalent vin Working capabilities o-fyamuch'l-arge'r protractor of theusual type.

' yThe instrument shown in Figure 2 is designed more'as 4a Working toolfor use by artisans and in manual training-schools'. As

shown, it comprises a sheet 14; of material out outof this sheet 14to'leave plates .19 connecting the angles B and D toV stamped out toAform a quadrilateral ABCD similar to the quadrilateral ABCD. Triangularportions 15, 16,17V and 18 are stiffening the center ruling member 20.This ruler member 2O is provided Wit-h a slot 21, di-v vided by astiening bar 22, having the straight edge 23 line in the line AO. IProtractor scales 24 are provided on the sides 'AB and AD, land havetheir common center at the point 25 in the y'edge 23 of the slot 2l.

ln order to adapt this polygon for edge Vcontara with a boardor .otherobject, vflanges 26 are stamped u p fromslieet 1 4 at right angles tothe plane of the sheet. The approximate shapes vof these flangesareshovvn by the developed outlines 27 thereof, and the flangesterminate at .the points 28 equidistant from the edge 2 3 of the slot21, to give the instrument the function of a center-square. Its usenfor.this purpose Awill be obvious from the drawing, in Which the edge 23 ofthe instrunient as applied to arci-role 29 is shown Yas intersecting thediameter 30, previously ydrawn by edge 23, at the center f Y Theexpression drafting polygon, as used in the claims ofthis application,refers to a plate of thin material, orits framed equi-valent, having.straightedged cut-out or formed portions, providing straight rulingedges fixed at various angles to each other, and incapable kofmovementrelative to each other. .m

l claim e v l. A .drafting polygon having fourgstraight edges arrangedto form aiquadrilateral, the interior angles ofwhich are angles ofsixty, ninety, and one hundred and live degrees.

2. A .draftingpolygon having four straight edges arranged to form aquadrilateralof which tvvo sides are equal to each other and arearranged at an angle of ninety'degrees to each othel` and of which thetwo remaining sides are equal to'each otherk and arearranged at an angleof sixty degrees to .each other. Y l

3. A drafting polygon as set forth in claim l and having a. triangularportion cut out and providing three straight ruling edges .forming atriangle the' interior angles. of

which are angles of thirty, forty-five, and one hundred and fivedegrees.

e. A. drafting polygonl having four `straight edges arranged to form aquadriother and its two remaining. sides equal and :arrangedfat an angleof ninety degrees to each other land also :hav-ing portions thereof cutout to provide a ruler member extending bet-Ween said angles and havingstraight ruling edges parallel to a l-inejoining .and bisicting each ofsaid angles. f i

5. A drafting polygon including a straightedged ruler and a` pair ofrulers `extending lsynnnetrically from `opposite sides of .said rulerand having similar synnnetricaly arranged Vthereon relativev to saidruler andhaving their `centers lying on opposite edges of said ruler. n

6. A drafting polygon shaped as a quadriprotractor scales lateral havingtwo of its acent sides equal to each other and having a ruler member'provided with a center line bisecting the an- 7 A drafting polygonshaped as a quad-V rilateral having two of its adjacent sides equal toeach other and the 4other two sides equal to each other but of differentlengths from Jthe first named sides'rsaid quadrilateral vbeing pro-videdwith a slot having a straight edge coincident with a line bisecting thevangles between each of the two pairs of y adjacent sides.

8; A. drafting polygon as set forth in claim L in which the cuto'utportions are triangular and similar and are syinetrically ar-vranged on each side of said bisecting line to form ruling straight edgesarranged at angles of fifteen and thirty degrees to each of the polygonsides which are arranged at an angle of sixty to each other. Intestimony whereof I have signed my 'naine te this specification.

Josnrii nnen-ii.

